When I travel for 2 weeks, I bring a large suitcase with 4 wheels and a small one (could be a duffel or carry-on) to bring on the plane in case the large one doesn't make it to my destination. They are from the same brand so they were made to stack well with each other so I don't have a problem. For a shorter trip I bring a carry-on (four wheels) and a duffel.